An increasing number of applications today make use of digital video for various purposes including, for example, remote business meetings via video conferencing, high definition video entertainment, video advertisements, and sharing of user-generated videos. As technology is evolving, people have higher expectations for video quality and expect high resolution video with smooth playback at a high frame rate.
There can be many factors to consider when selecting a video coder for viewing digital video. Some applications may require excellent video quality where others may need to comply with various constraints including, for example, bandwidth or storage requirements. To permit higher quality transmission of video while limiting bandwidth consumption, a number of video compression schemes are noted including proprietary formats such as VPx (promulgated by On2 Technologies, Inc. of Clifton Park, N.Y.), H.264 standard promulgated by ITU-T Video Coding Experts Group (VCEG) and the ISO/IEC Moving Picture Experts Group (MPEG), including present and future versions thereof. H.264 is also known as MPEG-4 Part 10 or MPEG-4 AVC (formally, ISO/IEC 14496-10).
Modern video coding methods adjust certain compression parameters at a level of granularity that is smaller than a whole frame. For example, some compression schemes adjust the type or strength of the loop filter applied to macroblock or block boundaries to improve video quality shown to the viewer. Further, for example, a different quantization level can be applied to each macroblock in a frame. In this manner, macroblocks with important information can be transmitted at a high bit rate whereas macroblocks with less important information can be transmitted at a low bit rate.